Arc suppression device for plasma processing equipment

ABSTRACT

The present disclosure relates to plasma generation systems particularly applicable to systems which utilize plasma for semiconductor processing. A plasma generation system consistent with the present disclosure includes an arc suppression device coupled to the RF generator. The arc device includes switches that engage upon a triggering signal. In addition, the arc device includes a power dissipater to be engaged by the set of switches to dissipate both stored and delivered energy when the set of switches engage. The arc suppression device also includes an impedance transformer coupled to the power dissipater to perform an impedance transformation that, when the switches are engaged in conjunction with the power dissipater, reduces the reflection coefficient at the input of the device. The plasma generation system further includes a matching network coupled to the radio frequency generator and a plasma chamber coupled to the matching network.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of, incorporates byreference, and claims priority to co-pending U.S. patent applicationSer. No. 16/456,598 having the same inventorship and title as theinstant application, which is incorporated by reference herein for allapplicable purposes.

BACKGROUND

Plasma arc events which occur during plasma vapor deposition processescan cause yield-reducing defects in the fabrication of integratedcircuits on semiconductor wafers. Plasma arc events often result inflashes of light and heat that resemble a type of electrical dischargethat results from a low-impedance connection through air to ground orother voltage phase in an electrical system. Furthermore, a plasma arcevent can also cause a rapid release of energy due to fault eventsbetween phase conductors, phase conductors and neutral conductors, orbetween phase conductors and ground points.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, examples inaccordance with the various features described herein may be morereadily understood with reference to the following detailed descriptiontaken in conjunction with the accompanying drawings, where likereference numerals designate like structural elements.

FIG. 1 is an illustration of a plasma generation system which includesan arc suppression device, according to a system and method of thepresent disclosure.

FIG. 2 is an illustration of an arc suppression device, according to asystem and method of the present disclosure. In some examples, the arcsuppression device of FIG. 2 may be used to implement the arcsuppression device of the plasma generation system of FIG. 1 .

FIG. 3 is an illustration of a matching network which includes an arcsuppression device, according to a system and method of the presentdisclosure.

FIG. 4 is a Smith Chart which displays the transformation characteristicof the disclosed system on impedances with low resistive parts andinductive reactive parts.

FIG. 5 is a Smith Chart which displays the transformation characteristicof the disclosed system on impedances with low resistive parts andcapacitive reactive parts.

FIG. 6 is a Smith Chart which displays the transformation characteristicof the disclosed system on impedances with high resistive parts andinductive reactive parts.

FIG. 7 is a Smith Chart which displays the transformation characteristicof the disclosed system on impedances with high resistive parts andcapacitive reactive parts.

FIG. 8 is a Smith Chart which displays the pathway of impedancetransformation of the disclosed system on example impedance with highresistance and no reactance.

FIG. 9 is a Smith Chart which displays the pathway of impedancetransformation of the disclosed system on example impedance with lowresistance and no reactance.

FIG. 10 is a Smith Chart which displays the pathway of impedancetransformation of the disclosed system on example impedance with lowresistance and inductive reactance.

FIG. 11 is a Smith Chart which displays the pathway of impedancetransformation of the disclosed system on example impedance with lowresistance and capacitive reactance.

FIG. 12 is a flowchart of a method of suppressing an arc event,according to a system and method of the present disclosure.

DETAILED DESCRIPTION

The description of the different advantageous implementations has beenpresented for purposes of illustration and is not intended to beexhaustive or limited to the implementations in the form disclosed. Manymodifications and variations will be apparent to persons having ordinaryskill in the art. Further, different implementations may providedifferent advantages as compared to other implementations. Theimplementation or implementations selected are chosen and described inorder to best explain the principles of the implementations, thepractical application, and to enable persons having ordinary skill inthe art to understand the disclosure for various implementations withvarious modifications as are suited to the particular use contemplated.

Before the present disclosure is described in detail, it is to beunderstood that, unless otherwise indicated, this disclosure is notlimited to specific procedures or articles, whether described or not. Itis further to be understood that the terminology used herein is for thepurpose of describing particular implementations only and is notintended to limit the scope of the present disclosure.

Plasma processing systems use, for example, radio-frequency (“RF”) powerto initiate and sustain a plasma, with the RF energy coupled into a gasby an inductive and/or capacitive plasma coupling element. In someimplementations, an RF power source supplies RF power to a plasmacoupling element (e.g., coil or electrodes) which, in turn, excites thegas into a plasma within a plasma region of a process chamber. Thegenerated plasma is then used to process a substrate (e.g., asemiconductor wafer).

A plasma is often sustained in a portion of its current-voltagecharacteristic known as the abnormal glow regime. In this regime, sincea high density of electrons and ions are present, and becausesignificant electric fields are also present, the plasma is susceptibleto plasma arcing (“arcing”). Arcing is a condition in which the regionof current flow in a plasma normally spreads over a significant volumeand collapses into a highly localized region (called an “arcing region”)that contains a concentrated arcing current. During arcing, surfaces ofthe substrate or the system components can be altered or damaged fromion or electron implantation, from sputtering of the surfaces and/orlocalized heating which can cause spalling due to the high concentrationof power dissipation and the high speeds attained by electrons and ionsin the arcing region.

While normal metal deposition is typically less than one micron, arcingcan cause a locally thicker deposition of metal on a semiconductorwafer. When arcing occurs, the energy of the electromagnetic fieldwithin the plasma chamber can be focused on a smaller region of thetarget than intended, which can dislodge a solid piece of the target.The dislodged solid piece of target material may be large relative tothe thickness of the uniform coating expected on the wafer, and if alarge piece falls upon the semiconductor wafer, it may cause a defect inthe integrated circuit being formed on the semiconductor wafer at thatlocation.

In RF systems, impedance matching is important to maximize powertransfer. Herein, an impedance is defined as the total opposition of adevice or circuit to the flow of an alternating current (“AC”) at agiven frequency and is represented as a complex quantity which can begraphically shown on a vector plane. An impedance vector consists of areal part (resistance, R) and an imaginary part (reactance, X) and canbe expressed using the rectangular-coordinate form: Z=R+Xj. As known inthe art, reactance varies with frequency when the effect of resistanceis constant regardless of frequency.

In electronics, impedance matching is the practice of transforming therelationship between voltage and current in phase and amplitude suchthat the input impedance of an electrical load or the output impedanceof its corresponding signal source maximizes power transfer or minimizessignal reflection from the load. A primary role in any impedancematching scheme is to force a load impedance to appear as the complexconjugate of the source impedance such that maximum power can betransferred to the load. Any reactance between the source resistance andthe load resistance reduces the current in the load resistance and withit the power dissipated in the load resistance. To restore thedissipation to the maximum that occurs when the source resistance equalsthe load resistance, the net reactance of the transmission loop is equalto zero. This occurs when the load and source impedances are made to becomplex conjugates of another so they have the same real parts andopposite type reactive parts. If the source impedance is Zs=R+Xj, thenthe complex conjugate would be Zs*=R−Xj.

The present disclosure provides an impedance transformer (e.g., a90-degree (i.e., 90°) or quarter-wave impedance transformer) to be usedin conjunction with a pair of resistive terminations to transform animpedance caused by a plasma arc event (e.g., arcing). An impedancetransformer may include a coaxial transmission line, a broadside coupledtransmission line, an embedded transmission line, or a waveguide.However, these are merely examples and the present disclosure is notlimited thereto.

An impedance transformer may be realized by inserting a section of atransmission line with appropriate electrical length and characteristicimpedance. For example, a quarter-wave impedance transformer may be usedto match real impedances. However, a complex load impedance can also betransformed to a real impedance by adding a series or shunt reactivecomponent. Notably, a quarter-wave transformer can provide a match at aparticular operating frequency as well as an acceptable match across abandwidth of one octave, or less, depending on the quality factor, Q, ofthe transformation and the application.

The present disclosure provides a plasma generation system utilizingplasma for processing a substrate such as a semiconductor wafer.Notably, the present disclosure provides a novel arc suppression devicewhich can respond to an electrical signal when arcing occurs and canfurther reduce the energy being supplied to a plasma chamber when thesignal is received. In addition, the arc suppression device disclosedherein can reduce the reflection coefficient (e.g., gamma) as seen by aRF generator in a power delivery system.

FIG. 1 is an illustration of a plasma generation system 100 whichincludes an arc suppression device 102, according to a system and methodof the present disclosure. As shown, in addition to the arc suppressiondevice 102, the plasma generation system 100 includes a RF generator101, a matching network 103, and a plasma chamber 104, all coupled by aseries of transmission lines 105 a-105 c.

The RF generator 101 provides power to be delivered via the transmissionlines 105 a-105 c to the plasma chamber 104. The RF generator 101 mayoperate at many different frequencies. For example, the RF generator 101may operate at low frequencies (e.g., 30 kHz->300 kHz), mediumfrequencies (e.g., 300 kHz->3 MHz), high frequencies (e.g., 3 MHz->30MHz), and very high frequencies (e.g., 30 MHz->300 MHz), according toone or more examples of the present disclosure.

Notably, the present disclosure presents the RF generator 101 with astable load (e.g., approximately 50 ohms) even during unexpected events(e.g., plasma arcing) which may cause drastic changes to the impedancewithin the plasma chamber 104. During arcing, an impedance changesrapidly within the plasma chamber 104 which can shift the load-line, andhence, the efficiency and stability of the RF generator 101 therebycausing spurious emissions, etc. Advantageously, the arc suppressiondevice 102 can divert the energy supplied by the RF generator 101 fromthe process chamber that is feeding the plasma arc, thereby suppressing,or at least, mitigating the arc event. The arc suppression device 102may be equipped with sensor(s) (e.g., optical or electrical sensors) 106which determine when arcing occurs and provides a triggering signal ortriggering signals to the arc suppression device 102 when arcing isdetected.

Advantageously, as will be explained in more detail below, the arcsuppression device 102 may include a set of switching elements which canreact quickly such that the arc suppression device 102 can react on theorder of microseconds or less. The set of switching elements may includea PIN diode, silicon carbide field effect transistor (“SiCFET”), metaloxide semiconductor field effect transistor (“MOSFET”), insulated-gatebipolar transistor (“IGBT”), or bipolar junction transistor (“BJT”). Itshould be understood, however, that the present disclosure is notlimited to the aforementioned examples of switching elements. Inaddition, some implementations may have the switching elements 210,211ganged together or operated individually.

It should be understood by a person having ordinary skill in the artwith the benefit of this disclosure that the actual impedance within theplasma chamber 104 is not practically measured accurately along thetransmission lines 105 a-105 c during a process operation. The systemdescribed in this disclosure may operate effectively regardless of theload impedance.

The matching network 103 may include a plurality of reactive elements;and a controller 107 configured to provide a respective control signalto each of the actuating devices for the plurality of reactive elements.In response to the respective control signal provided thereto, eachreactive element is actuated in accordance with that control signal. Thematching network 103 can take the impedance presented by the plasmachamber 104 and transform it to a desired source impedance (e.g., 50ohms). However, it is common for automatic impedance matching networksused in plasma processing systems to used tunable elements driven by amotor. It may take the matching network 103 hundredths of milliseconds,or more, to react to sharp changes in load impedance. In some cases, thematching network 103 may be unable to tune acutely if the event hasresulted in load impedances outside of the range of the matchingnetwork.

FIG. 2 is an illustration of an arc suppression device 200, according toa system and method of the present disclosure. In some examples, the arcsuppression device 200 may be connected to a RF power port 201 along atransmission line 202. The arc suppression device 200 includes two shuntnetworks (e.g., elements) 213, 214 and a 90-degree, pi-network impedancetransformer 212. In one implementation, each shunt network 213, 214includes a power dissipater 216 (e.g., a resistor), one or morecapacitive elements 220, and a switching element 210, 211. The90-degree, pi-network impedance transformer 212 may be coupled to thepower dissipater 216 to perform an impedance transformation, that whenthe set of switching elements are engaged in conjunction with the powerdissipater 216, reduces the reflection coefficient at the input of thedevice 200. In one implementation, the reflection coefficient is reducedto a range of 0-0.5 (e.g., VSWR no greater than 3:1)

In one implementation, shunt network 214 takes the impedance present atnode 203 (e.g., impedance within a plasma chamber) and places thisimpedance in parallel therewith. The 90-degree, pi-network impedancetransformer 212 then transforms the resulting impedance 90 degrees.Lastly, the shunt network 213 takes the impedance transformed by the90-degree, pi-network impedance transformer 212 and places thisimpedance in parallel therewith.

The arc suppression device 200 can transform a high impedance to a lowimpedance, and vice versa, to within a target VSWR (e.g., 3:1).Moreover, the arc suppression device 200 can transform an impedance witha negative phase angle to an impedance with a positive phase angle, andvice versa, within a target VSWR.

It should be understood by a person having ordinary skill in the artthat the arc suppression device 200 is not limited to a pair of shuntnetworks 213, 214. In some implementations, a pair of shunt networks213, 214 may be replaced with a series configuration.

The power dissipater 216 may include a resistive element that isnon-inductive. The power dissipater 216, when engaged by the switchingelements 210, 211, dissipates both stored and delivered energy withinthe system. In the implementation shown, the power dissipater 216 has avalue of 130 ohms whereas the capacitive element has a value ofapproximately 0.01 ρF. However, these values are merely exemplary and donot limit the present disclosure. The value of the power dissipater 216determines the degree of energy that is dissipated and the amount thatthe reflection coefficient seen by the RF generator is minimized.

The arc suppression device 200 includes three primary components: aswitching element (e.g., switching elements 210, 211) to engage (e.g.,close) or disengage (e.g., open), an impedance transformer (e.g.,90-degree, pi-network impedance transformer 212) which can invert theimpedance presented by the plasma chamber (e.g., plasma chamber 104 inFIG. 1 ), and a power dissipater (e.g., power dissipater 216) to divertand dissipate the stored energy from the plasma chamber.

In one implementation, the switching elements 210, 211 engage upon atriggering signal or triggering signals. For example, the triggeringsignal may be the result of a change in reflection coefficient of atleast 0.5. However, the present disclosure is not limited thereto. Inaddition, a triggering signal may be a change in current, voltage, orreflection coefficient which exceeds a pre-determined threshold oversome period of time. Furthermore, the triggering signal may be acomposite of multiple sensed signals distributed throughout the plasmageneration system.

A triggering signal may be provided to the arc suppression device 200 bythe RF generator. In addition, the radio frequency plasma chamber mayinclude a sensor that determines when an arc event occurs and provide atriggering signal to the arc suppression device 200 when the arc eventhas been detected.

The switching elements 210, 211 may be mounted to the arc suppressiondevice 200 by a heatsink (not shown). In addition, the switchingelements 210, 211 may react to the triggering signal on an order ofmicroseconds or less. In addition, when the switching elements 210, 211engage, the arc suppression device 200 network transforms the plasmaload impedance to some new impedance with a low reflection coefficientto the RF power port 201 regardless of plasma load impedance anddissipates stored energy from the plasma processing module, according tosome implementations. Alternatively, when the switching elements 210,211 disengage, the arc suppression device 200 appears as a filter with50-ohm input and output impedance. When the switching elements 210, 211disengage, the switching elements 210, 211 prevent current from flowinginto the power dissipaters 216 and capacitive elements 220 so the shuntnetworks 213/214 appear as an open circuit. In one implementation, eachof the switching elements 210, 211 is a symmetric FET switch whichincludes silicon carbide field effect transistors (“SiCFET”) withfloating gate drive circuitry for medium frequency (“MF”) RF powersystems.

In other implementations, the switching elements 210, 211 include PINdiodes with a high voltage, bipolar-bias power supply. In addition, theswitching elements 210, 211 may include SiCFETs, metal oxidesemiconductor field effect transistors (“MOSFETS”), insulated-gatebipolar transistors (“IGBT”), or bipolar junction transistors (“BJTs”)so as long as doing so does not depart from the spirit and scope of thepresent disclosure. Switching elements 210, 211, as shown in the figure,can isolate or connect terminations to ground.

The switching elements 210, 211 may be engaged by switch actuator 207via transmission lines 208, 209. Switch actuator 207 may be also coupledto a digital isolator 206 which provides electrical and/or galvanicisolation between high-voltage RF waveforms in the RF power generationsystem and the triggering signal. The digital isolator 206 can becoupled to a trigger 205 as further shown in FIG. 2 .

As mentioned above, the arc suppression device 200 may include a networkthat performs a quarter-wave impedance transformation to make use ofboth dissipative terminations. The network takes the parallelcombination of the input impedance of the match, which is the plasmaload impedance transformed by the matching network, and the firsttermination and rotates it by a quarter wavelength so that the RFgenerator is presented an impedance equal to the parallel combination ofthis new impedance and the second termination. This mechanism guaranteesa minimization of gamma seen by the RF generator and is a function ofthe characteristic impedance of the system, the characteristic impedanceof the transformer (e.g., typically the same impedance), and thetermination resistance. A quarter-wave impedance transformer may bedefined as a transmission line or waveguide of length one-quarterwavelength (A) with some known characteristic impedance. Thequarter-wave impedance transformer can present at its input node 203 thedual of the impedance with which it is terminated. In thisimplementation, it is preferable for some VHF and higher frequencyapplications where lumped elements are exceedingly small and difficultto construct with high current and voltage capability.

In one implementation, the 90-degree, impedance transformer 212 includesa lumped element pi-network (e.g. 90-degree pi-network transformer). Thepi-network performs the same impedance transformation as thetransmission line or waveguide but offers a much more limited bandwidth.In one implementation, a pi-network of lumped elements consists ofcapacitors in shunt network branches in addition to an inductor in aseries branch. This implementation is preferable for MF and HFapplications where the wavelength is exceedingly long.

In one example, the magnitude of the impedance presented by a plasmachamber (e.g., plasma chamber 104 in FIG. 1 ) may have become a lowimpedance, and the impedance, Z_(N), may be placed in parallel with thepower dissipation element (e.g., power dissipater 216) of a shuntnetwork by engaging the switch devices. As such, the first powerdissipater will not have a large impact on the resulting impedance(e.g., Z₁=Z_(L1)/Z_(N)). The resulting impedance, Z₁, is transformed tohave a high impedance (e.g., Z_(D)) by the 90-degree, pi-networkimpedance transformer. The transformed impedance, Z_(D), is then placedin parallel with the shunt network 214 (e.g., Z_(M)=Z_(L2)/Z_(D)) whichconforms the impedance towards the center of the Smith Chart (e.g., neara source impedance of 50 ohms). In some implementations, a combinationof switching elements 210, 211 can be flange-mounted on a water-cooledheatsink for high-power applications.

Alternatively, if the magnitude of the plasma impedance has become highwithin a plasma chamber (e.g., plasma chamber 104 in FIG. 1 ), theimpedance, Z_(N), is placed in parallel with a power dissipater 216 of ashunt network 213, 214 (e.g., Z₂=Z_(L1)/Z_(N)). Therefore, the resultingimpedance, Z₂, conforms to the center as a high impedance is placed inparallel with another high impedance. Further, the 90-degree, pi-networkimpedance transformer 212 can transform the impedance to a relative lowimpedance (e.g., Z_(D)). Afterwards, the transformed impedance, Z_(D),is then placed in parallel with a power dissipater 216 of the shuntnetwork 213 (e.g., Z_(M)=Z_(L2)/Z_(D)). The shunt network 213 may havelow impact on the resulting impedance.

FIG. 3 is an illustration of a matching network 300 which includes anarc suppression device 305, according to a system and method of thepresent disclosure. Matching networks may be used, particularly in radiofrequency applications, for matching the impedance or admittance of apower source to a load having a different impedance or admittance inorder to provide maximum power transfer to the load and to precludedamage to the power source from reflected energy due to the mismatch.Plasma load impedance may vary depending on variables such as generatorfrequency, delivered power, chamber pressure, gas composition, plasmaignition, in addition to unexpected plasma arc events. The matchaccounts for these variations in load impedance by varying electricalelements, typically vacuum variable capacitors, internal to the match tomaintain the desired input impedance.

Matching network 300 may contain reactive elements, meaning elementsthat store energy in electrical and magnetic fields as opposed toresistive elements that dissipate electrical power. The most commonreactance elements are capacitors, inductors, and coupled inductors butothers such as distributed circuits may also be used. Matching networkscan also include elements including transmission lines and transformers.In the implementation shown, the matching network 300 contains a singlecapacitive element 301 and an inductive element 302.

Most notably, the matching network 300 includes an arc suppressiondevice 303. However, it is notable that matching network 300 differsfrom the matching network 103 shown in FIG. 1 in that the matchingnetwork 300 contains an arc suppression device 303 whereas the plasmageneration system 100 (see FIG. 1 ) includes a separate arc suppressiondevice 102 (see FIG. 1 ) and matching network 103 (see FIG. 1 )components. Accordingly, the arc suppression system disclosed herein maybe implemented within a matching network in some implementations.

FIG. 4 is a Smith Chart 400 which displays the transformationcharacteristic of the disclosed system on impedances with low resistiveparts and inductive reactive parts. Accordingly, Smith Chart 400displays a region 402 of impedances with low resistive parts andinductive reactive parts which can be transformed into impedances thatare within a target VSWR 401. When the arc suppression device isengaged, impedances within region 402 will be transformed into theimpedances within region 403, which falls within the VSWR 401 as shownin the figure.

It should be understood by a person having ordinary skill in the artthat the regions 402, 403 are exemplary as the region 402 impedanceswith low resistive parts and inductive reactive parts and thetransformed region 403 may be greater than or less than that shown inthe example of FIG. 4 . Herein, an impedance with a low resistive partmay be defined as an impedance with a resistance of less than 50 ohmswhereas an impedance with a high resistive part may be defined as animpedance with a resistance of greater than 50 ohms. In particular, thetransformed region 403 may have a greater or lesser area on the SmithChart 400 depending upon the target VSWR 401. Moreover, the impedanceswithin the transformed region 403 are capacitive in accordance withimplementations which employ an arc suppression device with a 90-degree,pi-network impedance transformer.

In addition, FIG. 4 shows points 404, 405 which are within and outsideof the target VSWR 401, respectively. Accordingly, the arc suppressiondevice disclosed herein can transform any impedance with a low resistivepart and an inductive reactive part to an impedance within the targetVSWR 401 regardless to whether the initial impedance is within oroutside of the target VSWR 401.

FIG. 5 is a Smith Chart 500 which displays the transformationcharacteristic of the disclosed system on impedances with low resistiveparts and capacitive reactive parts. Accordingly, Smith Chart 500displays a region 502 with low resistive parts and capacitive reactiveparts which can be transformed into impedances that are within a targetVSWR 501.

A system and method disclosed herein can transform impedances with lowresistive part and capacitive reactive parts to acceptable impedances asillustrated by transformed region 503. Regions 502, 503 are exemplary asthe region 502 of impedances with low resistive part and capacitivereactive parts and the transformed region 503 may be greater than orless than what is shown in the example of FIG. 5 . As such, thetransformed region 503 may have a greater or lesser area on the SmithChart 500 depending upon the target VSWR 501. Moreover, the impedanceswithin the transformed region 503 are inductive in accordance withimplementations which employ an arc suppression device with a 90-degree,pi-network impedance transformer.

In addition, FIG. 5 also shows points 504, 505 which are within andoutside of the target VSWR 501, respectively. Accordingly, the arcsuppression device disclosed herein can transform any impedances withlow resistive part and capacitive reactive parts to an impedance withinthe target VSWR 501 regardless to whether the initial impedance iswithin or outside of the target VSWR 501.

FIG. 6 is a Smith Chart 600 which displays the transformationcharacteristic of the disclosed system on impedances with high resistiveparts and inductive reactive parts. Accordingly, Smith Chart 600displays a region 602 of impedances with high resistive parts andinductive reactive parts which can be transformed into impedances thatare within a target VSWR 601. Notably, region 602 of impedances withhigh resistive parts and inductive reactive parts and the region 402(see FIG. 4 ) of purely inductive, low impedances as illustrated in FIG.4 constitute the entire induction impedances collectively on the SmithChart 600. A person having ordinary skill in the art can appreciate thatthe top half of a standard Smith Chart represents the inductive regionof impedances thereon.

Regions 602, 603 are exemplary as the region 602 of impedances with highresistive parts and inductive reactive parts and the transformed region603 may be greater than or less than what is shown in the example ofFIG. 6 . As such, the transformed region 603 may have a greater orlesser area on the Smith Chart 600 depending upon the target VSWR 601.

As described herein, a system and method of the present disclosure cantransform impedances with high resistive parts and inductive reactiveparts into the transformed region 603 that is within a target VSWR 601.Notably, the impedances within the transformed region 603 are capacitivein accordance with implementations which employ an arc suppressiondevice with a 90-degree, pi-network impedance transformer.

In addition, FIG. 6 shows points 604, 605 which are within and outsideof the target VSWR 601, respectively. Accordingly, the arc suppressiondevice disclosed herein can transform any impedance with a highresistive part and inductive reactive part to an impedance within thetarget VSWR 601 regardless to whether the initial impedance is within oroutside of the target VSWR 601.

FIG. 7 is a Smith Chart 700 which displays the transformationcharacteristic of the disclosed system on impedances with high resistiveparts and capacitive reactive parts. Accordingly, Smith Chart 700displays a region 702 of impedances with high resistive parts andcapacitive reactive parts which can be transformed into impedances thatare within a target VSWR. Notably, region 702 of impedances with highresistive parts and capacitive reactive parts and the region 502 (seeFIG. 5 ) of impedances with low resistive parts and capacitive reactiveparts as illustrated in FIG. 5 constitute all capacitive impedancescollectively on the Smith Chart 700. A person having ordinary skill inthe art can appreciate that the bottom half of a standard Smith Chartrepresents the capacitive region of impedances thereon. Regions 702, 703are exemplary as the region 702 of impedances with high resistive partsand capacitive reactive parts and the transformed region 703 may begreater than or less than what is shown in the example of FIG. 7 . Assuch, the transformed region 703 may have a greater or lesser area onthe Smith Chart 700 depending upon the target VSWR 701.

Advantageously, the system and method of the present disclosure cantransform impedances with high resistive parts and capacitive reactiveparts into the transformed region 703 that is within a target VSWR 701.Notably, the impedances within the transformed region 703 are inductivein accordance with implementations which employ an arc suppressiondevice with a 90-degree, pi-network impedance transformer.

Lastly, FIG. 7 shows points 704, 705 which are within and outside of thetarget VSWR 701, respectively. Accordingly, the arc suppression devicedisclosed herein can transform any impedance with a high resistive partand a capacitive reactive part to an impedance within the target VSWR701 regardless to whether the initial impedance is within or outside ofthe target VSWR 701.

FIG. 8 is a Smith Chart 800 which displays the pathway of impedancetransformation of the disclosed system on example impedance with highresistance and no reactance. Accordingly, Smith Chart 800 displays animpedance transformation of an example high resistance and low reactancecomplex impedance. In the example shown in FIG. 8 , the point 801represents a complex impedance value of 2,500+0j ohms which istransformed into an impedance value of approximately 17.7+0.1j ohms asshown by the point 805 by an arc suppression device as previouslydisclosed. As shown, curves 802, 803, and 804 each show thecontributions to impedance transformation from the terminations in afirst and second shunt network (e.g., curves 802, 804) and by the90-degree, pi-network impedance transformer (curve 803).

In the implementation shown, the impedance of the load in the firsttermination (corresponding to curve 802) is approximately 130−1j ohmsand the impedance of the load in the second termination (correspondingto curve 803) is also approximately 130−1j ohms. Moreover, in theimplementation shown, the impedance seen at the first shunt network isapproximately 123.6−0.9j ohms, approximately 20.3+0.2j ohms at the90-degree, pi-network impedance transformer, and approximately 17.7+0.1johms at the second shunt network.

Notably, the resulting VSWR (2.849) and reflection coefficient (0.480<)180° of the transformed impedance is within a VSWR and reflectioncoefficient target range (e.g., 3:1 and 0.5, respectively). Moreover,the impedance represented by point 801 is transformed to by the point805 90-degrees in accordance with implementations which employ an arcsuppression device with a 90-degree, pi-network impedance transformer.

FIG. 9 is a Smith Chart 900 which displays the pathway of impedancetransformation of the disclosed system on example impedance with lowresistance and no reactance. Accordingly, Smith Chart 900 displays animpedance transformation of an example low resistance and low reactancecomplex impedance, according to a system and method of the presentdisclosure. In the example shown in FIG. 9 , the point 901 represents acomplex impedance value of 1+0j which is transformed to an impedancevalue of approximately 123.4−1.1j ohms as shown by the point 904 by anarc suppression device as previously disclosed. As shown, curves 902,903 each show the contributions to impedance transformation from theterminations in a first shunt network (e.g., curves 903) and by the90-degree, pi-network impedance transformer (curve 902). Notably, in theexample shown, the transformation is not significantly attributed to thesecond shunt network as compared to the impedance example shown in FIG.8 (see curve 802).

In the implementation shown, the impedance of the load in the firsttermination (corresponding to curve 902) is approximately 130−1j ohmsand the impedance of the load in the second termination (correspondingto curve 903) is approximately 130−1j ohms. Moreover, in theimplementation shown, the impedance present at the first shunt networkis approximately 1+0j ohms, approximately 2,420−97.2j ohms at the90-degree, pi-network impedance transformer, and approximately123.4−1.2j ohms at the second shunt network.

Notably, the resulting VSWR (2.468) and the reflection coefficient(0.425<−0.52°) of the transformed impedance is within a VSWR andreflection coefficient target range (e.g., 3:1 and 0.5, respectively).

FIG. 10 is a Smith Chart 1000 which displays the pathway of impedancetransformation of the disclosed system on example impedance with lowresistance and inductive reactance. Accordingly, Smith Chart 1000displays an impedance transformation of an example low resistance andhigh positive reactance complex impedance. In the example shown in FIG.10 , the point 1001 represents a complex impedance value of 1+50j ohmswhich is transformed into an impedance value of approximately 28.5−33.6johms as shown by the point 1005 by an arc suppression device aspreviously disclosed. As shown, curves 1002, 1003, and 1004 each showthe contributions to impedance transformation from the terminations in afirst and second shunt network (e.g., curves 1002, 1004) and by the90-degree, pi-network impedance transformer (curve 1003).

In the implementation shown, the impedance of the load in the firsttermination (corresponding to curve 1002) is approximately 130-1j ohmsand the impedance of the load in the second termination (correspondingto curve 1004) is approximately 130−1j ohms. Moreover, in theimplementation shown, the impedance present at the first shunt networkis approximately 17.5+43.1j ohms, approximately 20.2−49.8j ohms at the90-degree, pi-network impedance transformer, and approximately28.5−33.6j ohms at the second shunt network.

Notably, the resulting VSWR (2.749) and the reflection coefficient(0.487<−99°) of the transformed impedance is within a VSWR andreflection coefficient target range (e.g., 3:1 and 0.5, respectively).Moreover, the impedance represented by point 1001 is transformed toimpedance represented by the point 1005 ninety degrees in accordancewith implementations which employ an arc suppression device with a90-degree pi-network transformer.

FIG. 11 is a Smith Chart which displays the pathway of impedancetransformation of the disclosed system on example impedance with lowresistance and capacitive reactance. Accordingly, Smith Chart 1100displays an impedance transformation of a low resistance and highnegative reactance complex impedance. In the example shown in FIG. 11 ,the point 1101 represents a complex impedance value of 1−50j ohms whichis transformed into an impedance value of approximately 29.0+33.8j ohmsas shown by the point 1105 by an arc suppression device as previouslydisclosed. As shown, curves 1102, 1103, and 1104 each show thecontributions to impedance transformation from the terminations in afirst and second shunt network (e.g., curves 1102, 1104) and by the90-degree pi-network transformer (curve 1103).

In the implementation shown, the impedance of the load in the firsttermination (corresponding to curve 1102) is approximately 130−1j andthe impedance of the load in the second termination (corresponding tocurve 1103) is approximately 130−1j. Moreover, in the implementationshown, the impedance seen at the first shunt network is approximately17.3−42.9j ohms, approximately 20.4+50.2j ohms at the 90-degree,pi-network impedance transformer, and approximately 29.0−33.8j ohms atthe second shunt network.

The resulting VSWR (2.722) and the reflection coefficient (0.469<99°) ofthe transformed impedance is within a VSWR and reflection coefficienttarget range (e.g., 3:1 and 0.5, respectively). Furthermore, theimpedance represented by point 1101 is transformed to the impedancerepresented by point 1105 ninety degrees in accordance withimplementations which employ an arc suppression device with a 90-degree,pi-network impedance transformer. Notably, the curves 1102, 1103, and1104, which represent the impedance transformation associated withelements within the arc suppression device is a transposition, althoughquasi-symmetrical, to the impedance amplitude and phase angle associatedwith the example shown in FIG. 11 .

FIG. 12 is a flowchart 1200 of a method of suppressing an arc event,according to a system and method of the present disclosure. Flowchart1200 begins with block 1201 which includes employing an arc suppressiondevice to determine whether the reflection coefficient presented by thedevice has increased by 0.5, or more. As previously described, this maybe accomplished by an arc suppression device as depicted in FIG. 2 .Next, block 1202 includes employing the arc suppression device, as inthe example provided, such that the impedance presented to the RFgenerator produces a reflection coefficient of less than or equal to 0.5regardless of the state of the plasma processing module.

Furthermore, in the example provided, reducing power delivered to theplasma chamber by at least 3 dB in response to a change in gamma whichexceeds a pre-determined degree (e.g., greater than a 0.5 gamma shiftover a short time period), according to block 1203. As it would beunderstood by a person having ordinary skill in the art, a powerreduction of at least 3 dB is approximately 50% in power reduction.Accordingly, a 50% power reduction may be sufficient in many instancesto extinguish a plasma arc event. It is possible for design variationsto exist that result in different power reduction amounts by adjustingthe values of the termination resistors. It is also possible for thetrigger signal that engages/disengages the switching elements to beenacted as result of some change in operational parameters, such ascurrent, voltage, phase angle, spectral content, or some combination ofthese factors, as opposed to only being triggered by a sharp change ingamma.

Although the present disclosure has been described in detail, it shouldbe understood that various changes, substitutions and alterations can bemade without departing from the spirit and scope of the disclosure. Anyuse of the words “or” and “and” in respect to features of the disclosureindicates that examples can contain any combination of the listedfeatures, as is appropriate given the context.

While illustrative implementations of the application have beendescribed in detail herein, it is to be understood that the inventiveconcepts may be otherwise variously embodied and employed, and that theappended claims are intended to be construed to include such variations,except as limited by the prior art.

Reference throughout this specification to “one implementation” or “animplementation” means that a particular feature, structure, orcharacteristic described in connection with the implementation isincluded in at least one implementation of the present disclosure. Thus,the appearances of the phrases “in one implementation” or “in someimplementations” in various places throughout this specification are notnecessarily all referring to the same implementation. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more implementations.

In the foregoing specification, a detailed description has been givenwith reference to specific exemplary implementations. It will, however,be evident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the disclosure asset forth in the appended claims. The specification and drawings are,accordingly, to be regarded in an illustrative sense rather than arestrictive sense.

What is claimed is:
 1. A device, comprising: a first network comprising:a first switching element, including a first switch, to engage uponreceiving a triggering signal; and a first power dissipater to beengaged by the first switching element to dissipate both stored anddelivered energy when the first switching element engages; a secondnetwork comprising: a second switching element, including a secondswitch, to engage upon receiving the triggering signal; and a secondpower dissipater to be engaged by the second switching element todissipate both stored and delivered energy when the second switchingelement engages; and an impedance transformer coupled to each of thefirst power dissipater and the second power dissipator to perform animpedance transformation that, when the first switching element and thesecond switching element are engaged in conjunction with theirrespective power dissipater, reduces a reflection coefficient at aninput of the device, the first network and the second network beingdisposed on opposite sides of the impedance transformer.
 2. The deviceof claim 1, wherein each respective switching element includes at leastone of a PIN diode, silicon carbide field effect transistor (“SiCFET”),metal oxide semiconductor field effect transistor (“MOSFET”),insulated-gate bipolar transistor (“IGBT”), or bipolar junctiontransistor (“BJT”).
 3. The device of claim 1, wherein each of the firstswitch and the second switch reacts to the triggering signal on an orderof microseconds.
 4. The device of claim 1, wherein the impedancetransformer is a 90-degree impedance transformer that employs a lumpedelement pi-network.
 5. The device of claim 1, wherein the impedancetransformer is at least one of a coaxial transmission line, a broadsidecoupled transmission line, an embedded transmission line, or awaveguide.
 6. The device of claim 1, wherein the power dissipaterincludes a resistive element that is non-inductive.
 7. The device ofclaim 1, wherein the reflection coefficient is reduced to a range of0-0.5.
 8. The device of claim 1, wherein the switching elements can beengaged ganged, or actuated individually.
 9. The device of claim 1,wherein the triggering signal is the result of a change in reflectioncoefficient of at least 0.5.
 10. A matching network system, comprising:a matching network device, comprising: a plurality of reactive elements;and a controller configured to provide a respective control signal toeach of the actuating devices for the plurality of reactive elementssuch that, in response to the respective control signal providedthereto, each reactive element is actuated in accordance with thatcontrol signal; and an arc suppression device, comprising: a firstnetwork comprising: a first switching element, including a first switch,to engage upon receiving a triggering signal; and a first powerdissipater to be engaged by the first switching element to dissipateboth stored and delivered energy when the first switching elementengages; a second network comprising: a second switching element,including a second switch, to engage upon receiving the triggeringsignal; and a second power dissipater to be engaged by the secondswitching element to dissipate both stored and delivered energy when thesecond switching element engages; and an impedance transformer coupledto each of the first power dissipater and the second power dissipator toperform an impedance transformation that, when the first switchingelement and the second switching element are engaged in conjunction withtheir respective power dissipater, reduces a reflection coefficient atan input of the device, the first network and the second network beingdisposed on opposite sides of the impedance transformer.
 11. Thematching network system of claim 10, wherein the triggering signal is achange in current, voltage, or reflection coefficient that exceeds apre-determined threshold over some period of time.
 12. The matchingnetwork system of claim 10, wherein the first switching element and thesecond switching element connect their respective power dissipater toground.
 13. The matching network system of claim 10, wherein theengagement of the arc suppression device reduces the power delivered toa plasma chamber by at least 3 dB.
 14. A plasma generation system,comprising; a radio frequency generator; an arc suppression devicecoupled to the radio frequency (“RF”) generator, the arc suppressiondevice comprising: a first network comprising: a first switchingelement, including a first switch, to engage upon receiving a triggeringsignal; and a first power dissipater to be engaged by the firstswitching element to dissipate both stored and delivered energy when thefirst switching element engages; a second network comprising: a secondswitching element, including a second switch, to engage upon receivingthe triggering signal; and a second power dissipater to be engaged bythe second switching element to dissipate both stored and deliveredenergy when the second switching element engages; and an impedancetransformer coupled to each of the first power dissipater and the secondpower dissipator to perform an impedance transformation that, when thefirst switching element and the second switching element are engaged inconjunction with their respective power dissipater, reduces a reflectioncoefficient at an input of the device, the first network and the secondnetwork being disposed on opposite sides of the impedance transformer; amatching network coupled to the radio frequency generator; and a plasmachamber coupled to the matching network.
 15. The plasma generationsystem of claim 14, wherein the triggering signal is provided to the arcsuppression device by the RF generator.
 16. The plasma generation systemof claim 14, wherein the plasma chamber includes a sensor thatdetermines when an arc event occurs and provides the triggering signalto the arc suppression device responsive to the arc event determination.17. The plasma generation system of claim 16, wherein the sensor is atleast one of an optical sensor or an electrical sensor.
 18. The plasmageneration system of claim 14, wherein the triggering signal is acomposite of multiple sensed signals obtained at least in part byadditional sensors distributed throughout the plasma generation system.19. The plasma generation system of claim 14, wherein the impedancetransformer is further to, in conjunction with the first powerdissipater and the second power dissipater, perform an impedancetransformation to reduce the reflection coefficient at an input of thesystem to less than 0.5.
 20. The plasma generation system of claim 14,further comprising a digital isolator coupled to the arc suppressiondevice.